Engineering Dictionary
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An alphabetical listing of General terms and items. |
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a structural element formed from steel wire bound in strands; the suspending element in a bridge; the supporting element in some dome roofs
A bridge in which the roadway deck is suspended from cables anchored to one or more towers
A Irish castle dating from the 12th century which was based on the Norman `motte and bailey' castle.
A watertight, dry chamber in which people can work underwater
An affliction developed by people moving in and out of caissons quickly; also called the bends and decompression sickness
An equation that defines the resistance-temperature value of any pure metal that takes the form of RT = RO(1 + AT + BT2) for values between the ice point (0 C) and the freezing point of antimony (630.7 C) and the form RT = RO[1 + AT + BT2 + C(T-100)T2] between the oxygen point (-183.0 C) and the ice point (0 C).
The process of adjusting an instrument or compiling a deviation chart so that its reading can be correlated to the actual value being measured.
The quantity of thermal energy required to raise one gram of water 1 C at 15 C.
See gabion.
A projecting structure supported only at one end, like a shelf bracket or a diving board
The line bisecting the salient angle of a fortification. (L. caput, head).
(1) A covered passage that traverses a dry ditch from the curtain to the ravelin or from the covert way to an arrow or detached redoubt, covered on either side by a parapet and equipped with gun ports, through which cannon and muskets were used to sweep the ditch of enemy forces. (2) A single parapet at the entrance of the ditch in front of a ravelin, equipped with a small cannon, which were used to dispute the passage of the ditch.
A fortified hostel along a trade route.
The line which bisects the decumanus maximus or the centre line of a Roman fortification.
A field fortification formed by surrounding an army with armoured wagons. See gulaigorod,wagenburg.
Italian slender towers, usually connected to the house by a drawbridge, with no ground floor entrance, which could be used as a refuge in times in strife.
The entrance to a gallery which provided a vent for an enemy mine.
(1) A chamber within a tower used to house artillery away from the elements such as catapults, Greek from the 4th century BC. (2) A gallery which was built at the base of a fortifications wall from which defenders could fire into the faces of surface miners and battering ram parties. (3) A well having a number of underground branches which can be extended to intercept enemy mines. (4) A magazine for storage of explosives. (5) A place for quartering troops. (F. casemate, fr. It. casamatta, prob. from casa house + matto, f. matta, mad, weak, feeble, dim. from the same source as E. -mate in checkmate).
A Irish defensive enclosure consisting of a dry stone ring wall.
An Italian word meaning castle.
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a brittle alloy with high carbon content; iron that has been melted, then poured into a form and cooled; can be made into any shape desired
A flanking tower or redoubt attached to the vallum of a castra stativa, which was used to provide flanking fire at the gates, corners and at regular intervals along the ramparts, constructed of wood and earth or stone.
A small Byzantine frontier castle.
(1) A building constructed in the form of a castle. (2) A building provided with defences, such as battlements thus making it fortified. (3) An area provided with a castle.
A fortified manor house. See fortified manor.
A fortification, usually a castle.
The Norman word for castle.
(1) An Italian castle, which was mainly used as a fortified residence. (2) A term which generally refers to an Italian fortified village.
A small Roman detached fort or fortlet which served as a watch tower or signal station.
A fortified building or set of fortified buildings used to provide both active and passive defence, as well as a residence for the castles lord and household. See fortification, keep, tower. (L. castrum, fortress).
An Italian fortified settlement dating from the 10th to the 13th century. Usually sited on a hill top or spur, defences consisted of a surrounding curtain wall and a separate tower.
When a Roman encampment was reinforced by strengthening the ramparts with a wooden stockade or stone wall, it became more than just a temporary defence works, it became what is known as a `castra stativa'. The castra stativa served as a base from which actions could be launched into the surrounding area, and if necessary a place to fall back to if things did not go well. More elaborate castra stativa were provided with castellas or watch towers, which were used to flank the gates and at the corners and at regular intervals along the vallum. There were two types of castra stativa
A small fortified outpost of the Byzantine empire.
A positively charged ion (Na+, H+).
A gun platform which is raised higher that the rest of the works, used to command the surrounding works, usually situated on a bastion or curtain but were also sited in the gorges of bastions. Cavaliers were also built by besiegers to gain a commanding position. See gun platform. (L. caballus, horse).
A cannon battery in which the gun platform was raised above the level of the bastion. See cavalier.
The boiling of a liquid caused by a decrease in pressure rather than an increase in temperature.
A field fortification made of kneeling baggage animal (camels?). See kuklos. (Arabic)
A temperature scale defined by 0 C at the ice point and 100 C at boiling point of water at sea level.
A binding material, or glue, that helps concrete harden
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The center of gravity of a body is that point in the body through which passes the resultant of weights of its component particles for all orientations of the body with respect to a uniform gravitational field.
(1) The intersection made by two demigorges. (2) The point at which two adjacent curtains of a bastion intersect each other.
A force exerted on an object moving in a circular path which is exerted inward toward the center of rotation.
Polycrystalline ferroelectric materials which are used as the sensing units in piezoelectric accelerometers. There are many different grades, all of which can be made in various configurations to satisfy different design requirements.
High-temperature compositions of metal oxides used to insulate a pair of thermocouple wires The most common are Alumina (Al2O3), Beryllia (BeO), and Magnesia (MgO). Their application depends upon temperature and type of thermocouple. High-purity alumina is required for platinum alloy thermocouples. Ceramic insulators are available as single and multihole tubes or as beads.
The turves which were used to cover the outer face of the rampart of a Roman fortification, their purpose was to hold the ramparts in place. See gazion.
The volumetric flow rate of a liquid or gas in cubic feet per minute.
A letter, digit or other symbol that is used as the representation of data. A connected sequence of characters is called a character string.
For accelerometers that are rated in terms of charge sensitivity, the output voltage (V)is proportional to the charge (Q) divided by the shunt capacitance (C). This type of accelerometer is characterized by a high output impedance. The sensitivity is given in terms of charge; picocoulombs per unit of acceleration (g).
A fortification dating from the late 6th to the 13th century, which consisted of a position surrounded by earthen ramparts and ditches. The ancestors of the Ainu, the Ezo built the chashi to protect their region and the population centres from the depredations carried out by the armies of the Yamato court. These fortifications are found on the Japanese islands of Hokkaido and the north east of Honshu.
(1) Originally, a French castle, also known as a chateau-fort. (2) A French country residence. (O.Fr. chastel; L. castrum, fortress).
A fortified French chateau.
An India 14th century kiosk built over the main gate where the rule could see and be seen. (Indian)
The rapid cycling on and off of a relay in a control process due to insufficient bandwidth in the controller.
A sentry path or a passage around the revetment of a rampart which was provided with a small parapet. The position was used by musketeers keeping an eye on the glacis so as to prevent the placement of scaling ladders by the enemy. Later, it was generally discarded because of its susceptibility to artillery fire.
The curtain wall, or the additional counterguard wall surrounding a keep or attached to it. (L. camisia, shirt).
A foot bridge connecting the curtain wall to the entrance of a Norman keep of the 11th and 12th centuries. See flying bridge (2).
A medieval Korean defensive wall built by the Koryo dynasty from the Yalu river to the east coast.
A chromium-nickel alloy which makes up the positive leg of type K and type E thermocouples (registered trademarks of OMEGA ENGINEERING, INC.).
(1) A fortified church provided with defences such as battlements and arrow slits. (2) A church which was used as part of, or as a fortification.
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An obstacle consisting of sharpened branches set in a trench used to defend a Roman fort.
(1) A siege works constructed by a besieging army to protect their camp from sorties by the besieged garrison, consisting of encircling earthen ramparts and entrenchments. From the line of circumvallation attacks against the besieged position could be launched and further advancement of the earthworks could be constructed. In conjunction with the line of contravallation, these fortifications enable the besieging army to stop the flow of information, supplies and reinforcements reaching the besieged. (2) The process of carrying out the construction of lines of circumvallation. See circumvallatio, contravallation, counter vallation. (L. circum, round; vallum, rampart).
The ditch and rampart which was constructed by a besieging Roman army, which encircled a besieged city fortress, situated between the city and the Roman positions. See circumvallate.
A fortress in or near a city which was used to control the city and its inhabitants; providing a strong defensive position, and once the outer defences had fallen it could be used as a final refuge. (L. civis, citizen).
An engineer who plans, designs, and supervises the construction of facilities essential to modern life
The external or internal right angled extension of the rampart at the gateway of a Roman fort, which made the assailants turn to their left thus exposing their unshielded right side to the fire of the defenders on the ramparts and the castella.
To restore a device to a prescribed initial state, usually the zero state.
A fort which was situated on a spit of high ground and was protected on three sides by sheer cliffs, leaving only one line of approach which was defended by a rampart and ditch across the narrowest neck of the peninsula. If suitable headlands were not available, straight lines of cliff edges could be used by raising L or V shaped ramparts. Also known as a promontory fort, the majority occur on Britains western seaboard. Some can also be found on heights above rivers further inland. They were easily constructed and could be defended by only a small force, however, they had one major flaw, if an enemy did manage to break in it would have been impossible to escape.
The term applied to the phenomenon which occurs when an output signal is limited in some way by the full range of an amplifier, ADC or other device. When this occurs, the signal is flattened at the peak values, the signal approaches the shape of a square wave, and high frequency components are introduced. Clipping may be hard, as is the case when the signal is strictly limited at some level; or it may be soft, in which case the clipping signal continues to follow the input at some reduced gain.
The device that generates periodic signals for synchronization.
Total temperature variation from a desired set point of system. Expressed as "closeness of control" is 2 C or a system bandwidth with 4 C, also referred to as amplitude of deviation.
See quatrefoil keep.
The ability of a panel meter to eliminate the effect of AC or DC noise between signal and ground. Normally expressed in dB at dc to 60 Hz. One type of CMR is specified between SIG LO and PWR GND. In differential meters, a second type of CMR is specified between SIG LO and ANA GND (METER GND).
The AC or DC voltage which is tolerable between signal and ground. One type of CMV is specified between SIG LO and PWR GND. In differential meters, a second type of CMV is specified between SIG HI or LO and ANA GND (METER GND).
A sunken panel in a ceiling
A fortified dam retaining the water of a moat.
A temporary dam built to divert a river around a construction site so the dam can be built on dry ground
A frequency domain function computed to show the degree of a linear, noise-free relationship between a system's input and output. The value of the coherence function ranges between zero and one, where a value of zero indicates there is no causal relationship between the input and the output. A value of one indicates the existence of linear noise-free frequency response between the input and the output.
The ANSI established color code for thermocouple wires in the negative lead is always red. Color Code for base metal thermocouples is yellow for Type K, black for Type J, purple for Type E and blue for Type T.
a vertical, structural element, strong in compression
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When any work is constructed higher than another the work overlooking the other is said to command it.
The output form or type of control action used by a temperature controller to control temperature, i.e. on/off, time proportioning, PID.
The ability of an instrument to reject interference from a common voltage at its input terminals with relation to ground. Usually expressed in db (decibels).
Transmission and reception of data among data processing equipment and related peripherals.
A connector made of thermocouple alloys used to connect thermocouple probes and wires.
Alloys used to connect thermocouples to instrumentation. These alloys are selected to have similar thermal electric properties as the thermocouple alloys (however, only over a very limited temperature range).
Lead wire resistance compensation for RTD elements where an extra length of wire is run from the instrument to the RTD and back to the instrument, with no connection to the RTD.
An addition of specific materials or devices to counteract a known error.
A program that translates a high-level language, such as Basic, into machine language.
Any mathematically defined relationship given by the following expression:
The resultant form of a number of sinusoidal waves that are summed together forming a periodic wave. Such waves may be analyzed in the frequency domain to readily determine their component parts.
The space at the bottom of a caisson into which air is introduced under pressure to exclude water so that excavation can take place
a pressing force that squeezes a material together
The castle introduced into Europe in the late 12th century which consisted of two or more complete rings of bastioned curtain wall within one another, each increasing in height towards the keep in the centre. A variation on this design was were the gatehouse doubled as the keep. The aim of the design was to present the enemy with sides of equal strength at the time allowing a faster response to attack by the garrison. And with each ring of defence increasing in height towards the centre the defenders on the higher walls and towers could fire at the enemy over the lower defences, so that the amount of missile fire was increased compared to contemporary designs. If the outer defences fell to the enemy, they would be confronted by yet another line of defence; and each set of walls had to be taken completely before the attackers could move on to the next, thus increasing the losses to the besieging force as the siege continued. Also known as a multiple castle.
A mixture of water, sand, small stones, and a gray powder called cement
The measure of the ability of a solution to carry an electrical current. (See Equivalent Conductance)
The conveying of electrical energy or heat through or by means of a conductor.
The range (with a specified value of uncertainty, usually expressed in percent) within which the true value of a measured quantity exists.
For thermocouples and RTDs, the difference between the actual reading and the temperature shown in published tables for a specific voltage input.
An enclosure attached to the end of a thermocouple which can be cast iron, aluminum or plastic within which the electrical connections are made.
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See corbel.
A copper-nickel alloy used as the negative lead in Type E, Type J, and Type T thermocouples.
A person who coordinates the entire construction process -- from initial planning and foundation work through the structure's completion
Simple bridge made by linking one beam bridge to another; some of the longest bridges in the world are continuous span beam bridges
A frequency spectrum that is characterized by non-periodic data The spectrum is continuous in the frequency domain and is characterized by an infinite number of frequency components.
An uninterrupted wall walk around a curtain or tower wall, allowing the fast movement of equipment and troops to any quarter under attack. See bastille.
A hill fort which was constructed by reinforcing the natural defences of the position by digging a bank and ditch along the contour line surrounding a hill. See hill fort.
A series of field work consisting of earthen ramparts and ditches excavated parallel to the circumvallatio but facing outwards, which were used to protect the Roman encampments against the attack of a relieving army; and in conjunction with the circumvallatio, prevented supplies and reinforcements reaching the besieged city. See circumvallate, circumvallatio, contravallation.
A chain of redoubts and breastworks constructed by a besieging army which encircled a fortification, situated parallel to the circumvallation but facing the opposite direction. This set of works was used to protect the besiegers camp and positions from assault by a relieving army. See circumvallate, counter vallation.
A character whose occurrence in a particular context starts, modifies or stops an operation that effects the recording, processing, transmission or interpretation of data.
The output form or type of control action used by a temperature controller to control temperature, i.e., on/off, time proportioning, PID.
The temperature at which a system is to be maintained.
1. The circulatory motion that occurs in a fluid at a non-uniform temperature owing to the variation of its density and the action of gravity. 2. The transfer of heat by this automatic circulation of fluid.
A term used to refer to a merlon.
A projecting structure made of stone of wood located near the top of a wall, which were used to support such structures as; breteches, hourdings and machicolations. See bracket. (L. corvus, crow).
A bartizan built out on corbels, which was used to provide flanking fire thus reducing dead ground. See bartizan.
(1) A row of stones along the line of a rampart. (2) A continuous rounded coping at the top of a masonry revetment. (3) A chain of military posts.
Central region of a skyscraper; usually houses elevator and stairwell
A result of centripetal force on a mass moving with a velocity radially outward in a rotating plane.
A corner turret projecting only a small distance beyond the walls of a Norman rectangular keep; the turret had little if any military value as far as flanking ability was concerned. See square keep.
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A flanking tower projecting from the corner of a keep, which was used to flank the wall between the towers, and to protect the vulnerable corners from sapping by miners and battering rams.
A plane perpendicular to the shaft axis of a rotor in which correction for unbalance is made.
A measurement of the quantity of electrical charge, usually expressed as pico coulomb (10-12 coulombs).
Charge/unit acceleration, expressed in Pc/g (charge sensitivity).
A temporary work usually consisting of entrenchments built by the besieged forward of permanent fortifications, to check the approach of an enemy army.
An arch connecting two counterforts.
A mine dug to intercept the mine of a besieging force, so that a counter attack could be launched, the objective of which was to collapse the mine of the besiegers.
A salient in the opposite direction.
A trench which was excavated by the besieged in opposition to those of the besiegers. The parapet was turned against the enemy's approaches, and was flanked by artillery providing enfilade fire so that if the enemy took the trench it would be rendered useless.
The lines of earthworks thrown up by besiegers to protect their camp and positions from attack from a relieving army, used in conjunction with the lines of circumvallation during a siege of a fortification. See circumvallation, contravallation.
A weight added to a body so as to reduce a calculated unbalance at a desired place.
Any type of work which was used to oppose those of an enemy; an opposing work.
An inner buttress used to strengthen the masonry of a ramparts revetment.
An outwork, triangular in shape, open at the rear, situated before the face of a bastion, ravelin or redan, used to protect these works from enemy cannon fire.
(1) A strengthening wall built in front of another wall. (2) A wall which was built behind that of another as a reserve defence. (Fr. contremur).
The outer side of a ditch of a fortification, in some permanent fortifications it was faced with stone to make entering and retreating from the ditch more hazardous.
A gallery which located in the counterscarp of the salients, used to flank the ditch of a fortification.
The number of time intervals counted by the dual-slope A/D converter and displayed as the reading of the panel meter, before addition of the decimal point.
(1) An entrenchment made by the besieged behind a breach in the defences. (2) A passage through the glacis to allow the defenders to sally forth to attack an approaching enemy force. (Fr. couper, to cut).
Mobile wooden parapets attached to the inside walls, which were used in France around the 11th century.
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A space enclosed by walls or buildings. See bail, bailey, barbkin.
A castle where the domestic buildings were integrated into the curtain walls and arranged around a central courtyard. See keepless castle, quadrangular castle, quadrilateral castle.
A pathway or road running along the top of the counterscarp, provided with a protective enbankment which formed the crest of the glacis. The enbankment gave the soldiers standing in the covered way some protection from enemy fire, being high enough to obstruct the besiegers view. Also known as the covert way.
A pathway in front of the ditch protected by a parapet which formed the crest of the glacis. The covert way was used by soldiers who's job it was to break up the general line of assault. See covered way.
Cycles per second; the rate or number of periodic events in one second, expressed in Hertz (Hz).
Central processing unit. The part of the computer that contains the circuits that control and perform the execution of computer instructions.
An Irish fort or lake dwelling dating from the Bronze Age and used up to the 16th century which was located on islet, often an artificial one which was built up in a lake or marsh. (Ir. crann, tree).
(1) A zig-zag line of a fortification. (2) A sawtooth pattern on the inside line of a parapet. (Fr. pot hook).
To fortify or embattle.
A small loophole in the wall of a fortification, constructed with a widening aperture on the inside to allow the defenders a larger field of fire, but also allowing for the protection of the defenders. See loop.
A wooden shutter which covered a crenel and was used to defend a crenel, hinged at the top it enabled the defender to open the shutter to fire at the enemy, while gaining protection from the shutter in the closed position. See crenel.
The part of a parapet which is indented alternating with the solid uprights called merlons, which allowed the defenders to fire at the enemy while gaining protection from the merlons against the returned fire. See battlement, embrasure, reveal. (L. crena, a notch).
Fortified or provided with crenels. See battlemented, embattled.
A parapet consisting of merlons and crenels. The Licence to Crenellate was a royal licence giving permission to holder to build a fortification or to fortify a present building. See crenel, merlon, parapet.
The apex of the glacis, either formed by the parapet of the covered way, or where the glacis meets the top of the counterscarp. Also known as a ridge.
Critical damping is the smallest amount of damping at which a given system is able to respond to a step function without overshoot.
The rotational speed of the rotor or rotating element at which resonance occurs in the system. The shaft speed at which at least one of the "critical" or natural frequencies of a shaft is excited.
A gun loop provided with a cruciform sighting slit above the circular aperture for the cannon. The design came from adapting the cruciform arrow slit shape for the sighting slit, it provided effective sighting and a vent for the gases produced by cannon fire. See gun loop, gun port.
See cross and orb gun loop, gun port.
(1) A strong wall which divided a keep in half, the wall provided additional strength to the structure. (2) The wards between the walls of a type of concentric fortification were sectioned off by cross wall which ran between the outer and inner walls. If the enemy broke through the outer defences they were more easily disposed of (in a virtual killing ground).
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(1) An opening in the wall of a castle in the form of a cross for firing crossbows at an enemy without. (2) A cruciform aperture in the wall of a castle which was designed for the use of both bows and crossbows. Also known as a croslet arrow loop. See balistraria, loop.
A pathway around a traverse in the covered way.
To construct a work on the apex of the glacis or the top of a breach.
An outwork consisting of two long flanks and a front with a bastion and two demibastions, thus forming the shape of a crown.
An arrow slit provided with a horizontal slit, which was used to increase the available field of fire, dating form the end of the 12th century. See arrow loop, arrow slit.
A castle erected or modified by the 'Crusaders' to occupy and control their territorial gains in the Holy Land.
Measurement of temperature at extremely low values, i.e., below -200 C.
Canadian Standards Administration.
A trench or drainage ditch sunk into the floor of a main ditch. (It. lacuna, ditch).
The temperature at which a normally magnetic material goes through a magnetic transformation and becomes non-magnetic.
The rate of flow of electricity. The unit of the ampere (A) defined as 1 ampere = 1 coulomb per second.
An output form of a temperature controller which provides a current proportional to the amount of control required. Normally is a 4 to 20 milliamp current proportioning band.
See curtain wall.
The angle made by a flank (a work such as a bastion) with a curtain.
A tower which was a part of a curtain wall, from which defenders could provide flanking fire to the curtain wall since they usually projected further into the field. See bastion, mural tower, wall tower.
(1) A fortified wall which enclosed a bailey or ward. (2) The fortified wall which ran between two towers. (3) The rampart which ran between two bastions. See chemise, rampart.
A fortified residence of a Carolingian king.
A Frankish fortification of the 8th century constructed on a rectangular ground plan, using ditches and earthen ramparts topped by palisades.
A forward element of a Frankish fortification.
Curve fitting is the process of computing the coefficients of a function to approximate the values of a given data set within that function. The approximation is called a "fit". A mathematical function, such as a least squares regression, is used to judge the accuracy of the fit.
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The design of merlons underwent a change due to the fact that they were one of the most vulnerable parts of a fortification to artillery fire. The merlons were thickened and curved backwards, and the actual number of crenels was reduced. Also known as shot deflecting battlements. See merlon.
A wall consisting of round bastion which were built so close together that only a small portion of each protruded.
A method of tunnel construction that involves digging a trench, building a tunnel, and then covering it with fill
See cunette.
The time usually expressed in seconds for a controller to complete one on/off cycle.
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